Oxytocin
The positive and negative effects of the chemical known as the ‘love hormone’
A
Oxytocin is a chemical, a hormone produced in the pituitary gland in the brain. It was through
various studies focusing on animals that scientists first became aware of the influence of
oxytocin. They discovered that it helps reinforce the bonds between prairie voles, which mate for
life, and triggers the motherly behaviour that sheep show towards their newborn lambs. It is also
released by women in childbirth, strengthening the attachment between mother and baby. Few
chemicals have as positive a reputation as oxytocin, which is sometimes referred to as the ‘love
hormone’. One sniff of it can, it is claimed, make a person more trusting, empathetic, generous
and cooperative. It is time, however, to revise this wholly optimistic view. A new wave of
studies has shown that its effects vary greatly depending on the person and the circumstances,
and it can impact on our social interactions for worse as well as for better.( thesis)
B
Oxytocin’s role in human behaviour first emerged in 2005. In a groundbreaking experiments,
Markus Heinrichs and his colleagues at the University of Freiburg, Germany, asked volunteers to
do an activity in which they could invest money with an anonymous person who was not
guaranteed to be honest. The team found the participants who had sniffed oxytocin via a nasal
spray beforehand invested more money than those who received a placebo instead. The study
was the start of research into the effects of oxytocin on human interactions. ‘For eight years, it
was quite a lonesome field,’ Heinrichs recalls. ‘Now, everyone is interested.’ These follow-up
studies have shown that after a sniff of the hormone, people become more charitable, better at
reading emotions on others’ faces and at communicating constructively in arguments. Together,
the results fuelled the view that oxytocin universally enhanced the positive aspects of our social
nature.
C
Then, after a few years, contrasting findings began to emerge. Simone Shamay-Tsoory at the at
the University of Haifa, Israel, found that when volunteers played a competitive game, those who
inhaled the hormone showed more pleasure when they beat other players, and felt more envy
when others won. What’s more, administering oxytocin also has sharply contrasting outcomes
depending on a person’s disposition. Jennifer Bartz from Mount Sinai School of Medicine, New
York, found that it improves people’s ability to read emotions, but only if they are not very
socially adept to begin with. Her research also shows that oxytocin in fact reduces cooperation in
subjects who are particularly anxious or sensitive to rejection.
D
Another discovery is that oxytocin’s effects vary depending on who we are interacting with.
Studies conducted by Carolyn DeClerck of the University of Antwerp, Belgium, revealed that
people who had received a dose of oxytocin actually became less cooperative when dealing with
complete strangers. Meanwhile, Carsten De Dreu at the University of Amsterdam in the
Netherlands discovered that volunteers given oxytocin showed favouritism: Dutch men became
quicker to associate positive words with Dutch names than with foreign ones, for example.
According to De Dreu, oxytocin drives people to care for those in their social circles and defend
them from outside dangers. So, it appears that oxytocin strengthens biases, rather than promoting
general goodwill, as was previously thought.
E
There were signs of these subtleties from the start. Bartz has recently shown that in almost half
of the existing research results, oxytocin influenced only certain individuals or in certain
circumstances. Where once researchers took no notice of such findings, now a more nuanced
understanding of oxytocin’s effects is propelling investigations down new lines. To Bartz, the
key to understanding what the hormone does lies in pinpointing its core function rather than in
cataloguing its seemingly endless effects. There are several hypotheses which are not mutually
exclusive. Oxytocin could help to reduce anxiety and fear. Or it could simply motivate people to
seek out social connections. She believes that oxytocin acts as a chemical spotlight that shines on
social clues – a shift in posture, a flicker of the eyes, a dip in the voice – making people more
attuned to their social environment. This would explain why it makes us more likely to look
others in the eye and improves our ability to identify emotions. But it could also make things
worse for people who are overly sensitive or prone to interpreting social cues in the worst light.
F
Perhaps we should not be surprised that the oxytocin story has become more perplexing. The
hormone is found in everything from octopuses to sheep, and its evolutionary roots stretch back
half a billion years. ‘It’s a very simple and ancient molecule that has been co-opted for many
different functions,’ says Sue Carter at the University of Illinois, Chicago, USA. ‘It affects
primitive parts of the brain like the amygdala, so it’s going to have many effects on just about
everything.’ Bartz agrees. ‘Oxytocin probably does some very basic things, but once you add our
higher-order thinking and social situations, these basic processes could manifest in different
ways depending on individual differences and context.’
Questions 14-17
Reading Passage 2 has six section, A-F.
Which paragraph contains the following information?
Write the correct letter, A-F, in boxes 14-17 on your answer sheet.
NB You may use any letter more than once.
14 reference to research showing the beneficial effects of oxytocin on people
15 reasons why the effects of oxytocin are complex
16 mention of a period in which oxytocin attracted little scientific attention
17 reference to people ignoring certain aspects of their research data
Questions 18-20
Look at the following research findings (Questions 18-20) and the list of researchers below.
Match each research finding with the correct researcher, A-F.
Write the correct letter, A-F, in boxes 18-20 on your answer sheet.
18 People are more trusting when affected by oxytocin.
19 Oxytocin increases people’s feelings of jealousy.
20 The effect of oxytocin varies from one type of person to another.
List of Researchers
A
B
C
D
E
F
Markus Heinrichs
Simone Shamay-Tsoory
Jennifer Bartz
Carolyn DeClerck
Carsten De Dreu
Sue Carter
Questions 21-26
Complete the summary below.
Choose ONE WORD ONLY from the passage for each answer.
Write your answers in boxes 21-26 on your answer sheet.
Oxytocin research
The earliest findings about oxytocin and bonding came from research involving
21……………………….. It was also discovered that humans produce oxytocin during
22………………………… An experiment in 2005, in which participants were given either
oxytocin or a 23…………………………, reinforced the belief that the hormone had a positive
effect.
However, later research suggests that this is not always the case. A study at the University of
Haifa where participants took part in a 24……………………….. revealed the negative emotions
which oxytocin can trigger. A study at the University of Antwerp showed people’s lack of
willingness to help 25………………………. while under the influence of oxytocin. Meanwhile,
research at the University of Amsterdam revealed that people who have been given oxytocin
consider 26……………………….. that are familiar to them in their own country to have more
positive associations than those from other cultures.
……………………………………………………………………………………………….
Answers:
14. B
15. F
16. B
17. E
18. A
19. B
20. C
21. animals
22. childbirth
23. placebo
24. game
25. strangers
26. names